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Rational use of antibiotics
The document provides guidelines for the rational use of antibiotics, emphasizing the importance of accurate diagnosis, appropriate choice of antibiotics based on infection type, and considering patient-specific factors. It highlights the need for empirical therapy in critical cases, the necessity of culture and sensitivity studies for definitive therapy, and cautions against the misuse and over-prescribing of antibiotics. Additionally, it addresses the significance of cost-effectiveness and the potential adverse effects of various antibiotics.
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Introduction to antibiotic use highlighting their widespread and often irrational usage.
Key diagnostic questions to consider before prescribing antibiotics.
Presentation of a clinical case of a child with pneumonia and treatment course.
Indications and strategies for definitive, empirical, and prophylactic antibiotic therapy.
Factors influencing antibiotic choice, including the site, type, and severity of infections.
Differentiating infections based on anatomical location and corresponding recommended treatments.
Approach for treating infections that require special considerations for effective management.
The necessity of culturing and sensitivity testing in proper antibiotic management.
Differences in resistance patterns between community and hospital-acquired infections.
Impacts of patient age, pregnancy, metabolic abnormalities, and organ dysfunction on antibiotic therapy.
Pharmacokinetics, toxicity, and cost considerations affecting antibiotic therapy decisions.
Benefits and drawbacks of using combination therapy in antibiotic treatment.
Key guidelines for proper antibiotic use, avoiding misuse, and ensuring effective treatment.
A thank you note concluding the presentation on antibiotics.
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Rational use of antibiotics
- 1. General Guidelines forRational use of Antibiotics Dhaval Joshi
- 2. BACKGOUND • Antibiotics arethe most widely used medications • Perhaps the most irrationally used
- 3. Questions • Is itinfection? • Is it bacterial Infection? • If yes, take appropriate samples first • What is likely etiologic agent? • Which antibiotic? • Also consider some evidence!
- 4. Case • 5 yrsold boy • Fever and cough for 8 days • Admitted on day 2 of fever • Chest X-ray: right lower zone pneumonia • WBC count: 23,000/cumm • Prescribed with Ceftriaxone, Amikacin
- 5. Case • No improvementin chest x-ray, changed to meropenam in 3 days • Refereed on Day 3 meropenam for non respone
- 6. Case • Evidence ofpneumococcal vaccines • Amoxicillin
- 7. Indications for antibacterialtherapy 1. Definitive therapy 2. Empirical therapy 3. Prophylactic therapy
- 8. Empirical therapy • Empiricalantibacterial therapy should be restricted to critical cases, when time is inadequate for identification and isolation of the bacteria and reasonably strong doubt of bacterial infection exists • In such situations, drugs that cover the most probable infective agent/s should be used
- 9. Definitive therapy • Thisis for proven bacterial infections • Attempts should be made to confirm the bacterial infection by means of staining of secretions/fluids/exudates, culture and sensitivity, serological tests and other tests • Based on the reports, a narrow spectrum, least toxic, easy-to-administer and cheap drug should be prescribed
- 10. Prophylactic therapy • Antimicrobialprophylaxis is administered to susceptible patients to prevent specific infections that can cause definite detrimental effect • In all these situations, only narrow spectrum and specific drugs are used. It should be remembered that there is NO single prophylaxis to 'prevent' all possible bacterial infections
- 11. What antibacterial? • Thereare more than 100 antibacterials available today, and each one has its own spectrum of activity, adverse effect profile and cost • The prescriber should consider many factors before prescribing an antibacterial agent so as to make the treatment most effective with least adverse effects and cost
- 12. Factors affecting Antibiotic Prescribing Thefollowing factors should be considered while prescribing an antibacterial agent: • Site of infection • Type of infection • Severity of infection • Isolate and its sensitivity • Source of infection • Host factors • Drug related factors
- 13. Site of infection •As a Rule Of The Thumb, it can be remembered that the infections above the diaphragm are caused by Cocci and Gram positive organisms and • infections below the diaphragm are caused by Bacilli and Gram negative organisms, although there are exceptions
- 14. Infections above thediaphragm • Respiratory tract infections- Streptococcus pyogenes, S. pneumoniae, streptococci • Managed with Penicillins, Cephalosporins, Macrolides and Tetracyclines
- 15. Infections below thediaphragm • Examples include urinary tract infection, intra- abdominal sepsis, pelvic infections etc. and these are caused by the organisms like E. coli, Klebsiella, Proteus, Pseudomonas, etc. • Quinolones, Aminoglycosides, 3rd generation cephalosporins and Metronidazole, alone or in combination are useful in these infections
- 16. Site of infection •There are certain sites where the infection tends to be difficult for treatment • In such cases higher dose, more frequent administration, longer duration, antibacterial combinations and lipophilic antibacterials may have to be used
- 17. Type of infection •Infections can be localized or extensive; mild or severe; superficial or deep seated; acute, sub acute or chronic and extracellular or intracellular • For extensive, severe, deep seated, chronic and intracellular infections, higher and more frequent dose, longer duration of therapy, combinations, lipophilic drugs may have to be used
- 18. Severe infections • (bacteremia/ pyemia / sepsis syndrome / septic shock; abscesses in lung/ brain/ liver/ pelvis/ intra-abdominal; meningitis/ endocarditis/ pneumonias/ pyelonephritis/ / gangrene and hospital acquired infections) can be life threatening and rapidly fatal
- 19. Severe infections • Inall such situations therefore, attempts should be made to identify and isolate the infecting organism from the site as well as blood by staining culture • In treating the severe infections, drugs should be administered by only intravenous route to ensure adequate blood levels
- 20. Severe infections • Onlybactericidal drugs should be used to ensure faster clearance of the infection. If the site of infection is known, narrow spectrum drugs should be used • A combination of Penicillins/3rd generation cephalosporins, aminoglycosides and metronidazole may be used. The dose should be higher and more frequent. Whenever possible, a switch to oral therapy should be made
- 21. Isolate and sensitivity •Ideal management of any significant bacterial infection requires culture and sensitivity study of the specimen • Blood culture: Febrile illness • If the situation permits, antibacterials can be started only after the sensitivity report is available
- 22. Isolate and sensitivity •Narrow spectrum, least toxic, easy to administer and cheapest of the effective drugs should be chosen • If the patient is responding to the drug that has already been started, it should not be changed even if the in vitro report says otherwise
- 23. Source of infection •Community acquired infections are less likely to be resistant whereas hospital acquired infections are likely to be resistant and more difficult to treat (e.g. Pseudomonas, MRSA etc.)
- 24.
- 25. AGE • The patient’sage is an important factor both in trying to identify the likely etiologic agent and in assessing the patient’s ability to eliminate the drug(s) to be used • In infants, chloramphenicol (can cause gray baby syndrome) and sulfa (can cause kernicterus) are contraindicated
- 26. AGE • Elderly: Nephrotoxicdrugs • In the elderly, achlorhydria may affect absorption of antibacterial agents; drug elimination is slower, requiring dose adjustments; and ototoxicity of aminoglycosides may be increased • Increased absorption of penicillin G and decreased absorption of Ketoconazole
- 27. Pregnancy • In pregnancy,drugs with known toxicity or un- established safety like tetracyclines, quinolones, streptomycin, erythromycin and Clarithromycin are contraindicated in all trimesters • Sulfa, nitrofurantoin and chloramphenicol are contraindicated in the last trimester.
- 28. Pregnancy • Drugs withlimited data on safety like aminoglycosides, azithromycin, clindamycin, vancomycin, metronidazole, trimethoprim, rifampicin and pyrazinamide • Penicillins, cephalosporins, INH and ethambutol are safe in pregnancy • In lactating mothers sulfa, tetracyclines, metronidazole, nitrofurantoin and quinolones are contraindicated
- 29. Metabolic Abnormalities • Inheritedor acquired metabolic abnormalities will influence the therapy of infectious diseases in a variety of ways • Slow acetylators • G6PD deficiency
- 30. Organ Dysfunction • Inpatients with renal failure, tetracyclines are absolutely contraindicated • Aminoglycosides, cephalosporins, fluroquinolones and sulfa are relatively contraindicated; and
- 31. Organ Dysfunction • Penicillins,Macrolides, vancomycin, metronidazole, INH, ethambutol and rifampicin are relatively safe • It is better to avoid combinations of cephalosporins and aminoglycosides in these patients because both these classes of drugs can cause nephrotoxicity.
- 32. Organ Dysfunction • Inpatients with hepatic failure - chloramphenicol, erythromycin, fluroquinolones, pyrazinamide, rifampicin, INH and metronidazole are relatively contraindicated • Penicillins, cephalosporins, ethambutol and aminoglycosides are safe
- 33. Organ Dysfunction • Significantaccumulation can occur when both liver dysfunction and renal dysfunction are present for these drugs: cefotaxime, nafcillin, piperacillin, and sulfamethoxazole
- 34. Concomitant Disease States •Certain diseases will predispose patients to a particular infectious disease or will alter the type of infecting organism • Patients with immunosuppressive diseases, such as malignancies or acquired immunologic deficiencies, are highly predisposed to infections, and the types of organisms can be vastly different from what would be expected
- 35. Concomitant Disease States •Seizures-High doses of penicillin G • Patients with myasthenia gravis or other neuromuscular problems susceptible to the neuromuscular blocking effect of the aminoglycosides, polymyxins
- 36.
- 37. Pharmacokinetic and Pharmacodynamic Considerations •Integration of both pharmacokinetic and pharmacodynamic properties of an agent is important when choosing antimicrobial therapy to ensure efficacy and to prevent resistance • Aminoglycosides exhibit concentration- dependent bactericidal effects • β-Lactams display time-dependent bactericidal effects
- 38. Tissue Penetration • Cerebrospinalfluid (CSF) concentrations of antimicrobial agents necessary to cure bacterial meningitis have been defined • Drugs that do not reach significant concentrations in the CSF should either be avoided or instilled directly, if feasible
- 39. Tissue Penetration • Theproper route of administration for an antimicrobial depends on the site of infection • Parenteral therapy: febrile neutropenia or deep- seated infections such as meningitis, endocarditis, and osteomyelitis • Oral therapy: RTI, skin and soft tissue infections, uncomplicated urinary tract infections, and selected sexually transmitted diseases
- 40. Drug Toxicity • CNStoxicities: penicillins, cephalosporins, quinolones, and imipenem • Hematologic: nafcillin, piperacillin, cefotetan, chloramphenicol and trimethoprim • Nephrotoxicity: aminoglycosides and vancomycin
- 41. Drug Toxicity • Ototoxicity:aminoglycosides or erythromycin • Photosensitivity: azithromycin, quinolones, tetracyclines, pyrazinamide, sulfamethoxazole, and trimethoprim • Gastric toxicities
- 42. Cost • Lastly, thecost of therapy should be considered in choosing the antibacterial agent and in a developing country like India with limited spending on healthcare, this does assume significance • It should always be remembered that just because a particular drug is expensive, it need not be superior than the cheaper ones • For example, cheaper drugs like doxycycline or co- trimoxazole would be as effective as the costlier clarithromycin or cephalosporins in the management of LRTI
- 43. COMBINATION ANTIMICROBIAL THERAPY • Broadeningthe Spectrum of Coverage: Intraabdominal and female pelvic infections • Synergism: enterococcal endocarditis • Preventing Resistance: TB
- 44. COMBINATION ANTIMICROBIAL THERAPY • Thecombination of two or more antibiotics can result in antagonistic effects • Increased cost • Increased drug toxicity
- 45. General Guidelines Touse Antibiotics • Start antibiotics if there is evidence of infection • In starting antibiotics it is better not to use any of the new ones,if you are not familiar with their use • Antibiotics should not be started in response to patients pressure
- 46. General Guidelines Touse Antibiotics • No antibiotics- viral infections like Common cold or diarrhea to satisfy the patients • Antibiotics when used given for sufficient long period, Inadequate duration and dose of therapy should be discouraged • Do not change an antibiotic before giving the current antibiotic a fair trial
- 47. General Guidelines Touse Antibiotics • Cost effectiveness of therapy should be considered especially while changing the antibiotics, calculating for the full duration of treatment. • Wherever possible culture sensitivity of the sample should be sent before the antibiotic treatment started
- 48. General Guidelines Touse Antibiotics • Avoid using too many antimicrobials and drug combinations as it encourages poor diagnosis and its mismanagement • Avoid use of multiple antibiotics, except where it is indicate-TB • Acquire adequate and unbiased information about a limited number of antibiotics of proven efficacy and be familiar with their side effects
- 49. General Guidelines Touse Antibiotics • Get a full drug history and history of allergy to the chosen antibiotics, before starting the antibiotics • Where possible and indicated,e.g.poor response to therapy, repeat culture sensitivity • Avoid the use of topical antimicrobials,prophylactic antimicrobials and antimicrobial combinations
- 50.